Just got back from the track and got a few 13.5s@102mph but I still can only get a best of 2.03 60ft time. The problem is that I bog down on the launch if I launch at anything under 2,800rpms. Launch at 3K and the engine responds well, but at that point the tires can't handle it and it spins.

Its a Holley 650 DP on a 355 with World S/R Heads and xs268 cam. I've tried everything with the carburator....from a wide variety of different acc. pump squitters to different pump cams in a handful of different configurations. I just can't get it to not bog under 2,800rpms. I'm starting to think that maybe it has something to do with timing. Cause my timing comes all in at 2,900rpms(right where the thing starts to launch well with no bog). When launching at 2,200-2,600rpms, when I get the bog, it isn't getting full timing by 8-12 degrees. So the spark isn't getting enough 'jumpstart' on the sudden incoming fuel/air and it bogs. Does this make any sense? Do you guys who race launch with full timing? Does anyone think it would be advantageous to get all the timing in at 2,200rpms instead of 2,900rpms? (also will this introduce detonation on the street)

TTT, tell us about your launch technique, i.e., how do you let off the clutch? ( what type of clutch btw).

Its a Mcleod 11" Borg and Beck 3 finger clutch(guy at Mcleod said they can handle alot more then I put out-car is only running mid 13s).

Stage-press line-lock(i'll roll through the lights if I don't), bring up rpms, and bring clutch pedal up to just before it starts to engage, see the 3rd yellow, let go off line lock while releasing clutch(not side-stepping it but letting off with my foot very very quickly), and mash the gas to full throttle. Usually gets me decent R/Ts(.550-.650-best of .512)as long as the starter doesn't start the tree real quick(which he usually does and by the time I look up after setting the rpms its already on the 2nd yellow).

Who knows maybe its something with the carb. I could always put the 50cc acc. pump diagfram in. Bog did get better when I put 31 squiters fr./bk.(from stock 28s) but I just can't imagine my mild combo needs more accelerator pump shot.

I'd go to more squirter long before putting a 50cc on. I use a 37 with hollow screw in the front and a 35 in the rear both with 30cc pumps.